By Jan. 1 of this year, the Kyoto Protocol was supposed to have cut the world's greenhouse gas output by 5 percent compared with 1990 levels. While the signatories as a whole are likely to meet that target, in part because of the shutdown of Eastern European factories during the 1990s, global carbon emissions overall rose 54 percent during that same period, according to the Global Carbon Project.
As a result, many experts are engaged in a discussion over whether they should continue pressing for ambitious carbon cuts in the near term or adjust their goals in the face of the prospect of a much warmer world.
In 2004, Princeton University professors Robert Socolow and Stephen Pacala wrote an influential paper outlining how the world could stabilize its greenhouse emissions by mid-century through a series of "wedges," using current technology, such as sharply increasing nuclear power worldwide, eliminating deforestation and converting conventional plowing to no-tillage farming.
Now, Socolow has published an article in the Vanderbilt Law Review that he describes as his "let's get real here" lecture, in which he outlines what the world can realistically achieve over the next four decades. Environmentalists "don't think it's time to start the bargaining" on what's an appropriate climate target, Socolow said, but they need to adjust some of their goals in light of the projected temperature rise.
Compromises include capturing and storing carbon from power plants, he added, "since I don't think we can put the fossil fuel industry out of business."
At the same time, some researchers are pushing for much steeper emissions cuts. On Wednesday, the journal Environmental Research Letters will publish a paper showing that although Socolow and Pacala projected emissions could be stabilized by cutting 175 billion tons of carbon emissions over 50 years, accelerating emissions over the past decade mean that it could require more than 500 billion tons of avoided emissions to achieve the same goal.